Plug-in devices such as plug-in attenuators and equalizers are used in cable television (CATV) and other communications systems to correct or modify signals as they are transmitted throughout the systems over long lengths of cable. Conventionally, signal correction or modification is performed to maintain a desired signal response, which is typically a signal with a flat or sloped amplitude response over its frequency range, for optimal system processing of signals. For example, plug-in attenuators or the like are inserted in-line with transmission equipment, such as radio frequency (RF) amplifiers and other headend equipment, in a cable plant or head-end facility to attenuate a signal to a desired level. Similarly, plug-in equalizers or the like are inserted in-line with transmission equipment to level a signal throughout its frequency range to compensate for undesired frequency-related attenuation of the signal as it is transmitted over long lengths of cable.
Recent frequency expansion of existing CATV plants has been negatively impacted by excess high frequency roll-off, resulting in lower than optimum signal levels at the high end of the operating frequency range. For example, the excessive high frequency roll-off currently being encountered in 1 GHz cable plant expansions is due to the cascaded roll-off of several active and passive devices in the cable plant, many of which were installed when the cable plant was operating at 870 MHz and below.